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wm(3tk) Tk Built-In Commands wm(3tk) 





NAME


wm - Communicate with window manager






SYNOPSIS


wm option window ?args?








DESCRIPTION


The wm command is used to interact with window managers in
    order to control such things as the title for a window, its geometry, or the
    increments in terms of which it may be resized. The wm command can
    take any of a number of different forms, depending on the option
    argument. All of the forms expect at least one additional argument,
    window, which must be the path name of a top-level window.


The legal forms for the wm command are:



  

  
If minNumer, minDenom, maxNumer, and maxDenom
      are all specified, then they will be passed to the window manager and the
      window manager should use them to enforce a range of acceptable aspect
      ratios for window. The aspect ratio of window (width/length)
      will be constrained to lie between minNumer/minDenom and
      maxNumer/maxDenom. If minNumer etc. are all specified
      as empty strings, then any existing aspect ratio restrictions are removed.
      If minNumer etc. are specified, then the command returns an empty
      string. Otherwise, it returns a Tcl list containing four elements, which
      are the current values of minNumer, minDenom,
      maxNumer, and maxDenom (if no aspect restrictions are in
      effect, then an empty string is returned).

  

  

  

  

  

  
This subcommand returns or sets platform specific attributes associated
      with a window. The first form returns a list of the platform specific
      flags and their values. The second form returns the value for the specific
      option. The third form sets one or more of the values. The values are as
      follows:






All platforms support the following attributes (though X11 users
    should see the notes below):



  

  
Specifies the alpha transparency level of the toplevel. It accepts a value
      from 0.0 (fully transparent) to 1.0 (opaque). Values outside
      that range will be constrained. Where not supported, the -alpha
      value remains at 1.0.

  

  
Places the window in a mode that takes up the entire screen, has no
      borders, and covers the general use area (i.e. Start menu and taskbar on
      Windows, dock and menubar on macOS, general window decorations on
    X11).

  

  
Specifies whether this is a topmost window (displays above all other
      windows).




On Windows, the following attributes may be set.



  

  
Specifies whether the window is in a disabled state.

  

  
Specifies a toolwindow style window (as defined in the MSDN).

  

  
Specifies the transparent color index of the toplevel. It takes any color
      value accepted by Tk_GetColor. If the empty string is specified
      (default), no transparent color is used. This is supported on Windows
      2000/XP+. Where not supported, the -transparentcolor value remains
      at {}.




On macOS, the following attributes may be set.



  

  
Specifies the modification state of the window (determines whether the
      window close widget contains the modification indicator and whether the
      proxy icon is draggable).

  

  
Specifies process notification state (bouncing of the application dock
      icon).

  

  
Specifies the path of the file referenced as the window proxy icon (which
      can be dragged and dropped in lieu of the file's finder icon).

  

  
Makes the window content area transparent and turns off the window shadow.
      For the transparency to be effective, the toplevel background needs to be
      set to a color with some alpha, e.g.
    “systemTransparent”.




On X11, the following attributes may be set. These are not
    supported by all window managers, and will have no effect under older
  WMs.



  

  
Requests that the window should be interpreted by the window manager as
      being of the specified type(s). This may cause the window to be decorated
      in a different way or otherwise managed differently, though exactly what
      happens is entirely up to the window manager. A list of types may be used,
      in order of preference. The following values are mapped to constants
      defined in the EWMH specification (using others is possible, but not
      advised):







  

  
indicates a desktop feature,

  

  
indicates a dock/panel feature,

  

  
indicates a toolbar window that should be acting on behalf of another
      window, as indicated with wm transient,

  
  
indicates a torn-off menu that should be acting on behalf of another
      window, as indicated with wm transient,

  

  
indicates a utility window (e.g., palette or toolbox) that should be
      acting on behalf of another window, as indicated with wm
    transient,

  

  
indicates a splash screen, displayed during application start up,

  

  
indicates a general dialog window, that should be acting on behalf of
      another window, as indicated with wm transient,

  
  
indicates a menu summoned from a menu bar, which should usually also be
      set to be override-redirected (with wm overrideredirect),

  
  
indicates a popup menu, which should usually also be set to be
      override-redirected (with wm overrideredirect),

  

  
indicates a tooltip window, which should usually also be set to be
      override-redirected (with wm overrideredirect),

  

  
indicates a window that provides a background notification of some event,
      which should usually also be set to be override-redirected (with wm
      overrideredirect),

  

  
indicates the drop-down list of a combobox widget, which should usually
      also be set to be override-redirected (with wm
    overrideredirect),

  

  
indicates a window that represents something being dragged, which should
      usually also be set to be override-redirected (with wm
      overrideredirect),

  

  
indicates a window that has no special interpretation.







  

  
Requests that the window should be maximized. This is the same as wm
      state zoomed on Windows and macOS.




On X11, changes to window attributes are performed asynchronously.
    Querying the value of an attribute returns the current state, which will not
    be the same as the value most recently set if the window manager has not yet
    processed the request or if it does not support the attribute.





  

  
If name is specified, this command stores name (which should
      be the name of the host on which the application is executing) in
      window's WM_CLIENT_MACHINE property for use by the window
      manager or session manager. The command returns an empty string in this
      case. If name is not specified, the command returns the last name
      set in a wm client command for window. If name is
      specified as an empty string, the command deletes the
      WM_CLIENT_MACHINE property from window.

  

  
This command is used to manipulate the WM_COLORMAP_WINDOWS
      property, which provides information to the window managers about windows
      that have private colormaps.






If windowList is not specified, the command returns a list
    whose elements are the names of the windows in the
    WM_COLORMAP_WINDOWS property. If windowList is specified, it
    consists of a list of window path names; the command overwrites the
    WM_COLORMAP_WINDOWS property with the given windows and returns an
    empty string. The WM_COLORMAP_WINDOWS property should normally
    contain a list of the internal windows within window whose colormaps
    differ from their parents.


The order of the windows in the property indicates a priority
    order: the window manager will attempt to install as many colormaps as
    possible from the head of this list when window gets the colormap
    focus. If window is not included among the windows in
    windowList, Tk implicitly adds it at the end of the
    WM_COLORMAP_WINDOWS property, so that its colormap is lowest in
    priority. If wm colormapwindows is not invoked, Tk will automatically
    set the property for each top-level window to all the internal windows whose
    colormaps differ from their parents, followed by the top-level itself; the
    order of the internal windows is undefined. See the ICCCM documentation for
    more information on the WM_COLORMAP_WINDOWS property.





  

  
If value is specified, this command stores value in
      window's WM_COMMAND property for use by the window manager
      or session manager and returns an empty string. Value must have
      proper list structure; the elements should contain the words of the
      command used to invoke the application. If value is not specified
      then the command returns the last value set in a wm command command
      for window. If value is specified as an empty string, the
      command deletes the WM_COMMAND property from window.

  

  
Arrange for window to be displayed in normal (non-iconified) form.
      This is done by mapping the window. If the window has never been mapped
      then this command will not map the window, but it will ensure that when
      the window is first mapped it will be displayed in de-iconified form. On
      Windows, a deiconified window will also be raised and be given the focus
      (made the active window). Returns an empty string.

  

  
If active or passive is supplied as an optional argument to
      the command, then it specifies the focus model for window. In this
      case the command returns an empty string. If no additional argument is
      supplied, then the command returns the current focus model for
      window.






An active focus model means that window will claim
    the input focus for itself or its descendants, even at times when the focus
    is currently in some other application. Passive means that
    window will never claim the focus for itself: the window manager
    should give the focus to window at appropriate times. However, once
    the focus has been given to window or one of its descendants, the
    application may re-assign the focus among window's descendants. The
    focus model defaults to passive, and Tk's focus command
    assumes a passive model of focusing.





  

  
The window will be unmapped from the screen and will no longer be
      managed by wm. Windows created with the toplevel command
      will be treated like frame windows once they are no longer managed
      by wm, however, the -menu configuration will be remembered
      and the menus will return once the widget is managed again.

  

  
If window has been reparented by the window manager into a
      decorative frame, the command returns the platform specific window
      identifier for the outermost frame that contains window (the window
      whose parent is the root or virtual root). If window has not been
      reparented by the window manager then the command returns the platform
      specific window identifier for window.

  

  
If newGeometry is specified, then the geometry of window is
      changed and an empty string is returned. Otherwise the current geometry
      for window is returned (this is the most recent geometry specified
      either by manual resizing or in a wm geometry command).
      NewGeometry has the form
      =widthxheight±x±y,
      where any of =, widthxheight, or
      ±x±y may be omitted.
      Width and height are positive integers specifying the
      desired dimensions of window. If window is gridded (see
      GRIDDED GEOMETRY MANAGEMENT below) then the dimensions are
      specified in grid units; otherwise they are specified in pixel units.






X and y specify the desired location of
    window on the screen, in pixels. If x is preceded by +,
    it specifies the number of pixels between the left edge of the screen and
    the left edge of window's border; if preceded by - then
    x specifies the number of pixels between the right edge of the screen
    and the right edge of window's border. If y is preceded by
    + then it specifies the number of pixels between the top of the
    screen and the top of window's border; if y is preceded by
    - then it specifies the number of pixels between the bottom of
    window's border and the bottom of the screen.


If newGeometry is specified as an empty string then any
    existing user-specified geometry for window is cancelled, and the
    window will revert to the size requested internally by its widgets.


Note that this is related to winfo geometry, but not the
    same. That can only query the geometry, and always reflects Tk's current
    understanding of the actual size and location of window, whereas
    wm geometry allows both setting and querying of the window
    manager's understanding of the size and location of the window. This can
    vary significantly, for example to reflect the addition of decorative
    elements to window such as title bars, and window managers are not
    required to precisely follow the requests made through this command.





  

  
This command indicates that window is to be managed as a gridded
      window. It also specifies the relationship between grid units and pixel
      units. BaseWidth and baseHeight specify the number of grid
      units corresponding to the pixel dimensions requested internally by
      window using Tk_GeometryRequest. WidthInc and
      heightInc specify the number of pixels in each horizontal and
      vertical grid unit. These four values determine a range of acceptable
      sizes for window, corresponding to grid-based widths and heights
      that are non-negative integers. Tk will pass this information to the
      window manager; during manual resizing, the window manager will restrict
      the window's size to one of these acceptable sizes.






Furthermore, during manual resizing the window manager will
    display the window's current size in terms of grid units rather than pixels.
    If baseWidth etc. are all specified as empty strings, then
    window will no longer be managed as a gridded window. If
    baseWidth etc. are specified then the return value is an empty
    string.


Otherwise the return value is a Tcl list containing four elements
    corresponding to the current baseWidth, baseHeight,
    widthInc, and heightInc; if window is not currently
    gridded, then an empty string is returned.


Note that this command should not be needed very often, since the
    Tk_SetGrid library procedure and the setGrid option provide
    easier access to the same functionality.





  

  
If pathName is specified, it gives the path name for the leader of
      a group of related windows. The window manager may use this information,
      for example, to unmap all of the windows in a group when the group's
      leader is iconified. PathName may be specified as an empty string
      to remove window from any group association. If pathName is
      specified then the command returns an empty string; otherwise it returns
      the path name of window's current group leader, or an empty string
      if window is not part of any group.

  

  
If bitmap is specified, then it names a bitmap in the standard
      forms accepted by Tk (see the Tk_GetBitmap manual entry for
      details). This bitmap is passed to the window manager to be displayed in
      window's icon, and the command returns an empty string. If an empty
      string is specified for bitmap, then any current icon bitmap is
      cancelled for window. If bitmap is specified then the
      command returns an empty string. Otherwise it returns the name of the
      current icon bitmap associated with window, or an empty string if
      window has no icon bitmap. On the Windows operating system, an
      additional flag is supported:







  

  
If the -default flag is given, the icon is applied to all toplevel
      windows (existing and future) to which no other specific icon has yet been
      applied. In addition to bitmap image types, a full path specification to
      any file which contains a valid Windows icon is also accepted (usually
      .ico or .icr files), or any file for which the shell has assigned an icon.
      Tcl will first test if the file contains an icon, then if it has an
      assigned icon, and finally, if that fails, test for a bitmap.







  

  
Arrange for window to be iconified. It window has not yet
      been mapped for the first time, this command will arrange for it to appear
      in the iconified state when it is eventually mapped.

  

  
If bitmap is specified, then it names a bitmap in the standard
      forms accepted by Tk (see the Tk_GetBitmap manual entry for
      details). This bitmap is passed to the window manager to be used as a mask
      in conjunction with the iconbitmap option: where the mask has
      zeroes no icon will be displayed; where it has ones, the bits from the
      icon bitmap will be displayed. If an empty string is specified for
      bitmap then any current icon mask is cancelled for window
      (this is equivalent to specifying a bitmap of all ones). If bitmap
      is specified then the command returns an empty string. Otherwise it
      returns the name of the current icon mask associated with window,
      or an empty string if no mask is in effect.

  

  
If newName is specified, then it is passed to the window manager;
      the window manager should display newName inside the icon
      associated with window. In this case an empty string is returned as
      result. If newName is not specified then the command returns the
      current icon name for window, or an empty string if no icon name
      has been specified (in this case the window manager will normally display
      the window's title, as specified with the wm title command).

  

  
Sets the titlebar icon for window based on the named photo images.
      If -default is specified, this is applied to all future created
      toplevels as well. The data in the images is taken as a snapshot at the
      time of invocation. If the images are later changed, this is not reflected
      to the titlebar icons. Multiple images are accepted to allow different
      images sizes (e.g., 16x16 and 32x32) to be provided. The window manager
      may scale provided icons to an appropriate size.






On Windows, the images are packed into a Windows icon structure.
    This will override an ico specified to wm iconbitmap, and vice
  versa.


On X, the images are arranged into the _NET_WM_ICON X property,
    which most modern window managers support. A wm iconbitmap may exist
    simultaneously. It is recommended to use not more than 2 icons, placing the
    larger icon first.


On Macintosh, the first image called is loaded into an OS-native
    icon format, and becomes the application icon in dialogs, the Dock, and
    other contexts. At the script level the command will accept only the first
    image passed in the parameters as support for multiple sizes/resolutions on
    macOS is outside Tk's scope. Developers should use the largest icon they can
    support (preferably 512 pixels) to ensure smooth rendering on the Mac.





  

  
If x and y are specified, they are passed to the window
      manager as a hint about where to position the icon for window. In
      this case an empty string is returned. If x and y are
      specified as empty strings then any existing icon position hint is
      cancelled. If neither x nor y is specified, then the command
      returns a Tcl list containing two values, which are the current icon
      position hints (if no hints are in effect then an empty string is
      returned).

  

  
If pathName is specified, it is the path name for a window to use
      as icon for window: when window is iconified then
      pathName will be mapped to serve as icon, and when window is
      de-iconified then pathName will be unmapped again. If
      pathName is specified as an empty string then any existing icon
      window association for window will be cancelled. If the
      pathName argument is specified then an empty string is returned.
      Otherwise the command returns the path name of the current icon window for
      window, or an empty string if there is no icon window currently
      specified for window. Button press events are disabled for
      window as long as it is an icon window; this is needed in order to
      allow window managers to “own” those events. Note that not
      all window managers support the notion of an icon window, and the concept
      is entirely meaningless on non-X11 platforms.

  

  
The widget specified will become a stand alone top-level window.
      The window will be decorated with the window managers title bar, etc. Only
      frame, labelframe and toplevel widgets can be used
      with this command. Attempting to pass any other widget type will raise an
      error. Attempting to manage a toplevel widget is benign and
      achieves nothing. See also GEOMETRY MANAGEMENT.

  

  
If width and height are specified, they give the maximum
      permissible dimensions for window. For gridded windows the
      dimensions are specified in grid units; otherwise they are specified in
      pixel units. The window manager will restrict the window's dimensions to
      be less than or equal to width and height. If width
      and height are specified, then the command returns an empty string.
      Otherwise it returns a Tcl list with two elements, which are the maximum
      width and height currently in effect. The maximum size defaults to the
      size of the screen. See the sections on geometry management below for more
      information.

  

  
If width and height are specified, they give the minimum
      permissible dimensions for window. For gridded windows the
      dimensions are specified in grid units; otherwise they are specified in
      pixel units. The window manager will restrict the window's dimensions to
      be greater than or equal to width and height. If
      width and height are specified, then the command returns an
      empty string. Otherwise it returns a Tcl list with two elements, which are
      the minimum width and height currently in effect. The minimum size
      defaults to one pixel in each dimension. See the sections on geometry
      management below for more information.

  

  
If boolean is specified, it must have a proper boolean form and the
      override-redirect flag for window is set to that value. If
      boolean is not specified then 1 or 0 is returned to
      indicate whether or not the override-redirect flag is currently set for
      window. Setting the override-redirect flag for a window causes it
      to be ignored by the window manager; among other things, this means that
      the window will not be reparented from the root window into a decorative
      frame and the user will not be able to manipulate the window using the
      normal window manager mechanisms.






Note that the override-redirect flag is only guaranteed to be
    taken notice of when the window is first mapped or when mapped after the
    state is changed from withdrawn to normal. Some, but not all, platforms will
    take notice at additional times.





  

  
If who is specified, it must be either program or
      user, or an abbreviation of one of these two. It indicates whether
      window's current position was requested by the program or by the
      user. Many window managers ignore program-requested initial positions and
      ask the user to manually position the window; if user is specified
      then the window manager should position the window at the given place
      without asking the user for assistance. If who is specified as an
      empty string, then the current position source is cancelled. If who
      is specified, then the command returns an empty string. Otherwise it
      returns user or program to indicate the source of the
      window's current position, or an empty string if no source has been
      specified yet. Most window managers interpret “no source” as
      equivalent to program. Tk will automatically set the position
      source to user when a wm geometry command is invoked, unless
      the source has been set explicitly to program.

  

  
This command is used to manage window manager protocols. The name
      argument in the wm protocol command is the name of an atom
      corresponding to a window manager protocol. Examples include
      WM_DELETE_WINDOW or WM_SAVE_YOURSELF or
      WM_TAKE_FOCUS.






A window manager protocol is a class of messages sent from
    a window manager to a Tk application outside of the normal event processing
    system. The main example is the WM_DELETE_WINDOW protocol; these
    messages are sent when the user clicks the close widget in the title bar of
    a window. Handlers for window manager protocols are installed with the wm
    protocol command. As a rule, if no handler has been installed for a
    protocol by the wm protocol command then all messages of that
    protocol are ignored. The WM_DELETE_WINDOW protocol is an exception
    to this rule. At start-up Tk installs a handler for this protocol, which
    responds by destroying the window. The wm protocol command can be
    used to replace this default handler by one which responds differently.






The list of available window manager protocols depends on the
    window manager, but all window managers supported by Tk provide
    WM_DELETE_WINDOW. On the Windows platform, a WM_SAVE_YOURSELF
    message is sent on user logout or system restart.






If both name and command are specified, then
    command becomes the handler for the protocol specified by
    name. The atom for name will be added to window's
    WM_PROTOCOLS property to tell the window manager that the application
    has a handler for the protocol specified by name, and command
    will be invoked in the future whenever the window manager sends a message of
    that protocol to the Tk application. In this case the wm protocol
    command returns an empty string. If name is specified but
    command is not, then the current handler for name is returned,
    or an empty string if there is no handler defined for name (as a
    special case, the default handler for WM_DELETE_WINDOW is not
    returned). If command is specified as an empty string then the atom
    for name is removed from the WM_PROTOCOLS property of
    window and the handler is destroyed; an empty string is returned.
    Lastly, if neither name nor command is specified, the wm
    protocol command returns a list of all of the protocols for which
    handlers are currently defined for window.





  

  
This command controls whether or not the user may interactively resize a
      top-level window. If width and height are specified, they
      are boolean values that determine whether the width and height of
      window may be modified by the user. In this case the command
      returns an empty string. If width and height are omitted
      then the command returns a list with two 0/1 elements that indicate
      whether the width and height of window are currently resizable. By
      default, windows are resizable in both dimensions. If resizing is
      disabled, then the window's size will be the size from the most recent
      interactive resize or wm geometry command. If there has been no
      such operation then the window's natural size will be used.

  

  
If who is specified, it must be either program or
      user, or an abbreviation of one of these two. It indicates whether
      window's current size was requested by the program or by the user.
      Some window managers ignore program-requested sizes and ask the user to
      manually size the window; if user is specified then the window
      manager should give the window its specified size without asking the user
      for assistance. If who is specified as an empty string, then the
      current size source is cancelled. If who is specified, then the
      command returns an empty string. Otherwise it returns user or
      window to indicate the source of the window's current size, or an
      empty string if no source has been specified yet. Most window managers
      interpret “no source” as equivalent to program.

  

  
The stackorder command returns a list of toplevel windows in
      stacking order, from lowest to highest. When a single toplevel window is
      passed, the returned list recursively includes all of the window's
      children that are toplevels. Only those toplevels that are currently
      mapped to the screen are returned. The stackorder command can also
      be used to determine if one toplevel is positioned above or below a second
      toplevel. When two window arguments separated by either isabove or
      isbelow are passed, a boolean result indicates whether or not the
      first window is currently above or below the second window in the stacking
      order.

  

  
If newstate is specified, the window will be set to the new state,
      otherwise it returns the current state of window: either
      normal, iconic, withdrawn, icon, or (Windows
      and macOS only) zoomed. The difference between iconic and
      icon is that iconic refers to a window that has been
      iconified (e.g., with the wm iconify command) while icon
      refers to a window whose only purpose is to serve as the icon for some
      other window (via the wm iconwindow command). The
      icon state cannot be set.

  

  
If string is specified, then it will be passed to the window
      manager for use as the title for window (the window manager should
      display this string in window's title bar). In this case the
      command returns an empty string. If string is not specified then
      the command returns the current title for the window. The title for
      a window defaults to its name.

  

  
If container is specified, then the window manager is informed that
      window is a transient window (e.g. pull-down menu) working on
      behalf of container (where container is the path name for a
      top-level window). If container is specified as an empty string
      then window is marked as not being a transient window any more.
      Otherwise the command returns the path name of window's current
      container, or an empty string if window is not currently a
      transient window. A transient window will mirror state changes in the
      container and inherit the state of the container when initially mapped.
      The directed graph with an edge from each transient to its container must
      be acyclic. In particular, it is an error to attempt to make a window a
      transient of itself. The window manager may also decorate a transient
      window differently, removing some features normally present (e.g.,
      minimize and maximize buttons) though this is entirely at the discretion
      of the window manager.

  

  
Arranges for window to be withdrawn from the screen. This causes
      the window to be unmapped and forgotten about by the window manager. If
      the window has never been mapped, then this command causes the window to
      be mapped in the withdrawn state. Not all window managers appear to know
      how to handle windows that are mapped in the withdrawn state. Note that it
      sometimes seems to be necessary to withdraw a window and then re-map it
      (e.g. with wm deiconify) to get some window managers to pay
      attention to changes in window attributes such as group.








GEOMETRY MANAGEMENT


By default a top-level window appears on the screen in its
    natural size, which is the one determined internally by its widgets
    and geometry managers. If the natural size of a top-level window changes,
    then the window's size changes to match. A top-level window can be given a
    size other than its natural size in two ways. First, the user can resize the
    window manually using the facilities of the window manager, such as resize
    handles. Second, the application can request a particular size for a
    top-level window using the wm geometry command. These two cases are
    handled identically by Tk; in either case, the requested size overrides the
    natural size. You can return the window to its natural by invoking wm
    geometry with an empty geometry string.


Normally a top-level window can have any size from one pixel in
    each dimension up to the size of its screen. However, you can use the wm
    minsize and wm maxsize commands to limit the range of allowable
    sizes. The range set by wm minsize and wm maxsize applies to
    all forms of resizing, including the window's natural size as well as manual
    resizes and the wm geometry command. You can also use the command
    wm resizable to completely disable interactive resizing in one or
    both dimensions.


The wm manage and wm forget commands may be used to
    perform undocking and docking of windows. After a widget is managed by wm
    manage command, all other wm subcommands may be used with the
    widget. Only widgets created using the toplevel command may have an attached
    menu via the -menu configure option. A toplevel widget may be used as
    a frame and managed with any of the other geometry managers after using the
    wm forget command. Any menu associated with a toplevel widget will be
    hidden when managed by another geometry managers. The menus will reappear
    once the window is managed by wm. All custom bindtags for widgets in
    a subtree that have their top-level widget changed via a wm manage or
    wm forget command, must be redone to adjust any top-level widget path
    in the bindtags. Bindtags that have not been customized do not have to be
    redone.






GRIDDED GEOMETRY MANAGEMENT


Gridded geometry management occurs when one of the widgets of an
    application supports a range of useful sizes. This occurs, for example, in a
    text editor where the scrollbars, menus, and other adornments are fixed in
    size but the edit widget can support any number of lines of text or
    characters per line. In this case, it is usually desirable to let the user
    specify the number of lines or characters-per-line, either with the wm
    geometry command or by interactively resizing the window. In the case of
    text, and in other interesting cases also, only discrete sizes of the window
    make sense, such as integral numbers of lines and characters-per-line;
    arbitrary pixel sizes are not useful.


Gridded geometry management provides support for this kind of
    application. Tk (and the window manager) assume that there is a grid of some
    sort within the application and that the application should be resized in
    terms of grid units rather than pixels. Gridded geometry management
    is typically invoked by turning on the setGrid option for a widget;
    it can also be invoked with the wm grid command or by calling
    Tk_SetGrid. In each of these approaches the particular widget (or
    sometimes code in the application as a whole) specifies the relationship
    between integral grid sizes for the window and pixel sizes. To return to
    non-gridded geometry management, invoke wm grid with empty argument
    strings.


When gridded geometry management is enabled then all the
    dimensions specified in wm minsize, wm maxsize, and wm
    geometry commands are treated as grid units rather than pixel units.
    Interactive resizing is also carried out in even numbers of grid units
    rather than pixels.






BUGS


Most existing window managers appear to have bugs that affect the
    operation of the wm command. For example, some changes will not take
    effect if the window is already active: the window will have to be withdrawn
    and de-iconified in order to make the change happen.






EXAMPLES


A fixed-size window that says that it is fixed-size too:




toplevel .fixed
wm title     .fixed "Fixed-size Window"
wm resizable .fixed 0 0




A simple dialog-like window, centred on the screen:




# Create and arrange the dialog contents.
toplevel .msg
label  .msg.l  -text "This is a very simple dialog demo."
button .msg.ok -text OK -default active -command {destroy .msg}
pack .msg.ok -side bottom -fill x
pack .msg.l  -expand 1    -fill both
# Now set the widget up as a centred dialog.
# But first, we need the geometry managers to finish setting
# up the interior of the dialog, for which we need to run the
# event loop with the widget hidden completely...
wm withdraw .msg
update
set x [expr {([winfo screenwidth .] - [winfo width .msg]) / 2}]
set y [expr {([winfo screenheight .] - [winfo height .msg]) / 2}]
wm geometry  .msg +$x+$y
wm transient .msg .
wm title     .msg "Dialog demo"
wm deiconify .msg








SEE ALSO


toplevel(3tk), winfo(3tk)






KEYWORDS


aspect ratio, deiconify, focus model, geometry, grid, group, icon,
    iconify, increments, position, size, title, top-level window, units, window
    manager







  

    8.5
    Tk